The object of the present invention is to develop the necessary theoretical concepts and their corresponding manufacturing processes to obtain a traction-compression type of coupling between two structural components of which at least one is manufactured with composite materials. The coupling is achieved by means of the application of a certain number of bolts under traction, initially mounting said bolts with a pretension by means of applying a tightening torque and having the double object of (1) transmitting the existing loads between the two structural components mentioned, and (2) being possible to assemble and dismantle these two components.
Couplings with bolts of the traction-compression type applied on metals have a broad application, both in the machine field as well as within a wide range of vehicles, clearly indicating their usefulness.
In high performance composite materials, in which their degree of application and development is currently reduced due to their recent appearance in the art, these type of couplings has never been treated directly and in depth. Nevertheless, examples of couplings involving composite materials can be found in patent numbers U.S. Pat. Nos. 5,496,002, 4,228,976 and EP-A-0 732 262.
In recent years, the applicant has been working and developing structures in composite materials, whose coupling has been made under shear. However, it has been considered necessary to have the possibility of applying the dismountable traction-compression type of coupling and to fill this gap, the applicant has implemented a technological plan called L.S.S (Large Supporting Surfaces), in which one of its objectives is to develop the type of coupling, referred to in the present invention.
The present invention is applicable to one or both components of any type of structure which, having been manufactured with composite materials, has to be joined under load conditions of considerable traction, whilst, in turn, it is recommendable that they may be assembled and dismantled.
These components may be one of the parts of the complex structures belonging to:
Aircraft structures and controls (such as lining joints or fittings).
Spacecraft couplings.
Sea and land vehicles.
Industrial machinery and equipment.
The manufacturing processes involving them include:
Tape or tissue pre-impregnated laminates.
RTM (Resin-Transfer-Molding).
S/RFI (Stitched/Resin Film Infusion).
Filament winding.
Fiber siting.
The materials used may be integrated by different resins and types of fiber, such as:
Glass fiber.
Carbon fiber.
Kevlar.
Boron fiber.
The object of the invention is a process for making a dismountable and/or fixed traction-compression coupling to be applied to composite materials, in which a basic laminate of the composite material is folded at least once to obtain at least a skirt forming an angle of about 90xc2x0 to the rest of the laminate, by using a transition radius between the skirt and the rest of the laminate, and a set of distribution plates is applied over the basic laminate to stabilize the skirt and to produce a uniform load distribution, making holes in each set of distribution skirt-plates and introducing the traction bolts in said holes with an initial pretension, hence creating the connection between the two components to be joined.
The single or multiple skirts obtained as indicated above may be applied to flat or curved surfaces, as linings for the aerodynamic surfaces of aircraft and fittings.
The load distribution plates may be of metal or composite material.
According to the present invention, when a single basic laminate is being dealt with, situated on a simple surface, the folded skirt is bent towards one or other side of the reference surface or said skirt is partially bent towards both sides, such that the basic laminate branches off in two parts forming a kind of T.
Conversely, in the case of multiple basic laminates situated in different planes, the skirt of each laminate is bent towards one or other side of the reference surface or said skirt is partially bent towards both sides of said surface forming a kind of T and afterwards the skirts so formed are gradually superimposed to obtain a skirt grouping all the laminates to be joined in an interactive manner.
Likewise, according to the invention, if all or part of the laminates have a secondary nature, they are cut in a suitable transition process until forming a single skirt capable of concentrating within itself the load of all the other skirts and then, the single laminate obtained has its skirt folded towards one or other side of the reference surface or towards both sides of the latter forming a kind of T.
The invention is particularly applicable to the case in which the components to be joined consist of an aerodynamic surface lining-stringer assembly for aircraft structures, where the basic laminate skirt may be singly or multiply folded.
On the other hand, the specific loads of the aforementioned stringers may be integrated in the joint by folding its skirts or by cutting them and providing them continuity with local transition and reinforcement laminates.